This is a note to let you know that I've just added the patch titled
pwm: Zero-initialize the pwm_state passed to driver's .get_state()
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pwm-zero-initialize-the-pwm_state-passed-to-driver-s-.get_state.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1271a7b98e7989ba6bb978e14403fc84efe16e13 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@xxxxxxxxxxxxxx>
Date: Wed, 22 Mar 2023 22:45:45 +0100
Subject: pwm: Zero-initialize the pwm_state passed to driver's .get_state()
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From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
commit 1271a7b98e7989ba6bb978e14403fc84efe16e13 upstream.
This is just to ensure that .usage_power is properly initialized and
doesn't contain random stack data. The other members of struct pwm_state
should get a value assigned in a successful call to .get_state(). So in
the absence of bugs in driver implementations, this is only a safe-guard
and no fix.
Reported-by: Munehisa Kamata <kamatam@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230310214004.2619480-1-u.kleine-koenig@xxxxxxxxxxxxxx
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pwm/core.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -115,7 +115,14 @@ static int pwm_device_request(struct pwm
}
if (pwm->chip->ops->get_state) {
- struct pwm_state state;
+ /*
+ * Zero-initialize state because most drivers are unaware of
+ * .usage_power. The other members of state are supposed to be
+ * set by lowlevel drivers. We still initialize the whole
+ * structure for simplicity even though this might paper over
+ * faulty implementations of .get_state().
+ */
+ struct pwm_state state = { 0, };
err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);
trace_pwm_get(pwm, &state, err);
@@ -448,7 +455,7 @@ static void pwm_apply_state_debug(struct
{
struct pwm_state *last = &pwm->last;
struct pwm_chip *chip = pwm->chip;
- struct pwm_state s1, s2;
+ struct pwm_state s1 = { 0 }, s2 = { 0 };
int err;
if (!IS_ENABLED(CONFIG_PWM_DEBUG))
@@ -530,6 +537,7 @@ static void pwm_apply_state_debug(struct
return;
}
+ *last = (struct pwm_state){ 0 };
err = chip->ops->get_state(chip, pwm, last);
trace_pwm_get(pwm, last, err);
if (err)
Patches currently in stable-queue which might be from u.kleine-koenig@xxxxxxxxxxxxxx are
queue-6.2/pwm-zero-initialize-the-pwm_state-passed-to-driver-s-.get_state.patch
